Ophthalmological microscopes as such are known. They comprise a main objective, a magnification system disposed thereafter and a binocular system with eye-pieces (oculars). In order to provide a stereoscopic microscope, a splitting of a beam path passing through the main objective into a number of beam paths may be carried out in a magnification system, which may, for example, be provided as a zoom-system. Further, ophthalmological microscopes are known, which allow for a simultaneous viewing of an object by a first user (main surgeon) and a second user (assistant).
In order to carry out intraocular surgery, for example in order to microscopically view the fundus or parts of the vitreous body close to the fundus of a human eye, supplementary optical systems are needed at the stereoscopic microscopes. These consist of lenses, which are disposed in front of the main objective (on the side of the object). Since they are thus positioned outside the body of the microscope, they prove to be very disturbing for the operating surgeon, since they reduce the free working distance. Further, such supplementary optical systems are very sensitive to dirt, so that the sterility of such supplementary optical systems, which are disposed in such a way, is insufficient.
In the brochure “SDI II, BIOM II” of Oculus Optikgeräte GmbH dated 1998, as well as in U.S. Pat. No. 4,856,872, such a supplementary optical system is described. There, it may be seen that a lens system designed as a BIOM-system (BIOM: Binocoular Indirect Ophthalmomicroscope) protrudes downwards into the operation area and, for this reason, may be easily contaminated by the activity of the surgeon. Thereby, the lens, which is disposed close to the object (ophthalmoscopical lens), as well as the lens, which is disposed closer to the main objective (reduction lens) may be contaminated. In case of time consuming surgery, both lenses of this preceding supplementary optical system must be cleaned in regular intervals, which proves cumbersome.
A microscope comprising such a supplementary optical system is, for example, known from the German utility model G 94 15 219.5.
From DE 41 14 646 C2 there is known a solution, according to which an ophthalmological attachment for a surgical microscope is accommodated in an attachment housing, which is laterally positionable with respect to the main objective. The attachment comprises an ophthalmoscopical lens, an optical image erecting system and a slideable lens for focussing. The arrangement of these two lenses or lens systems in one housing is considered to be cumbersome. Also, such a housing proves to be disturbing for the surgeon in practical use.
From DE 35 28 356 A1, a device for examination and surgery of front and back eye areas is known. In this device for examination and surgery of the eye, an ophtalmological objective is combined with an operation microscope, the main objective of which is combined with an optical system of variable (frontal) focal lengths.